The genetically determined inability to secrete the water-soluble glycoprotein form of the ABO blood group antigens into saliva and other body fluids is a recognized risk factor for meningococcal disease. During a community-wide investigation of a prolonged outbreak of disease due to a B15: P1.16 sulphonamideresistant strain of Neisseria meningitidis in Stonehouse, Gloucestershire (the Stonehouse survey), the ABO blood group and secretor status of almost 5000 residents was determined.

The proportion of non-secretors in the Stonehouse population was significantly higher than the proportion of non-secretors among blood donors in the South West Region and in England generally. Seven of 13 Stonehouse residents with meningococcal disease who were tested were found to be non-secretors, a high proportion. The outbreak in Stonehouse cannot be explained solely in terms of the increased proportion of non-secretors. There was no clear correlation between the proportions of non-secretors in different areas within the town and the incidence of cases of meningococcal disease.

Carriers of meningococci, whether outbreak or other strains, were not more likely to be non-secretors. The reasons why non-secretors are more susceptible to meningococcal disease remain to be determined, but they do not appear to be related to carriage of meningococci.

One hundred and nine strains of Haemophilus influenzae type b were subtyped by sodium dodecyl sulphate polyacrylamide gel electrophoresis of whole-cell polypeptides. Twenty-one strains from England, 44 from Scotland, 8 from Sweden, 6 from the Netherlands and 30 from the USA were examined. Some of these strains had been subtyped by outer membrane protein analysis; most of the strains had been isolated from cases of invasive disease.

Comparison of polypeptide profiles using the Dice coefficient of similarity showed that the majority of European strains were closely related and formed a single large group. Four smaller groups were identified; three of these included American and European strains, indicating a world-wide distribution of subtypes. However, the common European and American subtypes fell into different groups, indicating the existence of marked geographical variations in subtype frequency.

Legionella pneumophila serogroup 1 was isolated from post mortem specimens from 13 out of 58 patients with pneumonia diagnosed at autopsy. The results of a study undertaken in the hospital environment showed that the water plumbing system was colonized with L. pneumophila serogroup 1 which could also be isolated from respiratory devices filled with tap water. Control measures instituted are described.

Following the occurrence of five cases of Legionnaires' disease among patients and therapists at a French hot spring spa, a series of cleansing procedures and an epidemiological study were undertaken. During a 3-month period, the spring water was repeatedly sampled. Serum samples were taken from 689 randomly selected patients, 230 therapists, 134 administrative staff and a control group of 904 blood donors.

Legionellaceae were present in the spring water at concentrations of 103–1055 colony forming units/1. Fifteen different species or serogroups were isolated with Legionella pneumophila serogroups 3 and 1 predominating. No clinical cases of Legionnaires disease were observed during the study. However, 11% of the therapists and 5% of the patients either had a high titre of antibody (≥256) to at least one species or serogroup or seroconverted during the study. Mean antibody titres in the three study groups were significantly higher than those in the blood donors against 11 of the 32 legionella antigens tested. Nine of these 11 antigens corresponded to species or serogroups isolated from the spring water. The highest mean antibody titres in all three study groups were against L. pneumophila serogroup 3, the most common legionella in the spring water.

These findings have important implications for the maintenance of adequate standards of hygiene, bacteriological sampling and clinical surveillance in this and similar establishments.

Genetic variation in isolates of Escherichia coli obtained mostly from urinary tract infections in humans and domesticated animals (dogs and cats) was assessed for 16 enzymes using multilocus enzyme electrophoresis to characterize chromosomal genotypes. A total of 148 isolates comprised 63 distinct electrophoretic types (ETs) and about half of the isolates belonged to one of 9 common ETs. A bootstrap analysis of genetic distance between ETs revealed three significant groups of strains. Variation in allele frequencies among groups accounted for 40% of the total genetic diversity. The majority of the common ETs fell into a major cluster of closely related strains. The recovery of multiple isolates of the same electrophoretic types and serotypes from unassociated hosts suggests that these bacteria represent uropathogenic clones that are widely disseminated in humans and animals

The presence of different Campylobacter jejuni serotypes in Swedish patients with diarrhoea and in Mexican patients with or without diarrhoea was investigated with special reference to repeated isolations during the course of infection and to symptomatic and asymptomatic episodes. The study included 136 C. jejuni isolates from 62 Mexican children and 173 isolates from 68 Swedish patients. The bacteria were serotyped for heat-stable (HS) and heat-labile (HL) antigen.

During a 4-month period during the summer of 1985, campylobacters were isolated from 338 (16·3%) of 2080 patients with acute diarrhoea attending the University Hospital of Infectious Diseases in Zagreb. Of these isolates 220 (64·1%) were Campylobacter jejuni and 118 (34·9%) were C. coli. The patients were drawn from three residential zones in and around Zagreb: inner city, peripheral city and rural. Incidences of campylobacter diarrhoea ranged from 71 per 100 000 per year in inner city residents to 99 per 100 000 per year in the rural residents. Most infections were in young children; the incidence in infants ranged from 800 to 2500 per 100 000 per year in the inner city and rural zones respectively. The isolation rate from faecal specimens of infants from the rural zone was 61%. The ratio of isolation rates in males and females (all ages) was 1·1:1, but in infants it was 0·7:1 and in patients over the age of 65 years it was 0·4:1. The incidence of C. coli in the rural zone was four times that in the inner city and twice that in the peripheral zone.

This survey shows that campylobacter infection in Zagreb has distinctive epidemiological features. The transmission of infection appears to be midway between that found in industrialized and developing countries, and there is an unexplained excess of C. coli infection.

We report an outbreak of serious infections with Serratia marcescens in patients on a neurosurgery ward. The epidemiological investigations undertaken are described. Features of outbreaks of infection with serratia and control measures are discussed.

Antisera were prepared in rabbits against seven well-characterized strains of Treponema hyodysenteriae of known serotype, and reacted in agarose gel double immunodiffusion tests (AGDP) with lipopolysaccharide (LPS) extracted from 18 Western Australian isolates of the organism. Eight isolates were provisionally typed by this method, but sera raised against one ‘typed’ and two ‘untypable’ local isolates reacted in an unexpected fashion with LPS from other local and type strains. Serum raised against the ‘typed’ local isolate reached with LPS from other previously untyped local isolates: this indicated the presence of more than one major LPS antigen amongst certain local isolates, and was confirmed by cross-absorption of sera. Sera raised against apparently untypable local isolates reacted with LPS from certain type organisms, thus suggesting the presence of complex antigenic relationships between LPS antigens.

The serotyping system for T. hyodysenteriae which was proposed by Baum &Joens (1979) uses unabsorbed antisera and is made unworkable by these observations. Instead we propose placing organisms which share common LPS antigens into serogroups A to E, members of which are defined by their reactivity with unabsorbed sera raised against a type organism for the group. We suggest strains B78, WAI, B169, Al and WA6 respectively as being the most suitable type organisms for the five serogroups identified so far. Isolates possessing additional unique LPS antigens can be regarded as serotypes within the serogroup. However the serotype of an isolate can only be established if antiserum is prepared against it, and this serum continues to react homologously after cross-absorption with bacteria from other serotypes within the serogroup.

Erythromycin resistance amongst group A streptococci (GAS) in Great Britain is a relatively rare occurrence and outbreaks have been sporadically reported. Over an 8-month period in 1986 ten associated cases occurred in the town of Bridgwater in Somerset. Isolates were group A, type M4 and resistant to erythromycin (MIC 8 mg/l) but sensitive to lincomycin and clindamycin. Erythromycin resistance was transferable from all isolates to a group A recipient strain. No plasmid DNA could be detected in the original isolates or transconjugants.

Five pigs were treated orally with norfloxacin for 5 consecutive days in two well-separated periods. This was done to determine the lowest dose required to free the pigs of Enterobacteriaceae. In the first period of the study, the animals were treated with 400 mg per day while in the second treatment 800 mg norfloxacin was given. Daily faecal culturing indicated that the faeces became free of Enterobacteriaceae in 3–5 days when treated with 400 mg/day, while all animals were found negative on culturing after 3 days of treatment with 800 mg/day. Investigation of the concentration of norfloxacin in the faeces revealed that a substantial fraction of the dose was either absorbed or inactivated by faecal substances. An in vitro study in faeces confirmed that a substantial part, some 75% of the dose, may have been inactivated by intestinal contents. This finding helps to explain the much lower concentration of 120 mg norfloxacin per kg of faeces in the pig in comparison with the almost tenfold higher concentration reported to develop in man during treatment with an identical dose.

Faraday Base represents a small isolated community producing its own domestic water by desalination of sea water. During the Antarctic winter of 1986 (April to October), regular bacteriological examination of the water supply and surrounding sea took place. Samples were collected and examined every 2 weeks by the methods described in the Department of Health and Social Security Report No. 71, on the Bacteriological Examination of Drinking Water Supplies (DHSS, 1982), for membrane filtration and colony counting. The results of these examinations are presented in this paper. The results obtained suggest that water of good bacteriological quality was produced by the desalination plant, but some samples from the distribution system contained coliforms or presumptive Escherichia coli in small numbers. The possible reasons for this low-level contamination are discussed. No cases of gastroenteritis occurred on the base during this time.

Among the 81 cultures of Salmonella typhimurium of phage type 141 examined, 72 had been isolated from Sheffield incidents in 1984–5 and 9 were Scottish isolates from 1986–7. All of these cultures from diverse sources belonged to primary biotype 31; 79 were of full biotype 31beg and 2 anaerogenic cultures were of full biotype 31begj. This is the first known occasion on which an epidemic strain of S. typhimurium of phage type/biotype 141/31beg has been implicated in outbreaks of human or animal infection in the UK. Because previous epidemic strains of S. typhimurium of phage type 141 in the UK belonged to biotypes 1f and 9f which are phylogenetically unrelated to biotype 31beg, the likely origin of this most recent epidemic S. typhimurium strain of phage type/biotype 141/31beg is discussed.

We describe an outbreak of Q fever affecting 16 of 32 employees at a truck repair plant. None of the cases were exposed to cattle, sheep or goats. the traditional reservoirs of Q fever. The cases did not work, live on, or visit farms or attend livestock auctions. One of the employees had a cat which gave birth to kittens 2 weeks prior to the first case of Q fever in the plant. The cat owner fed the kittens every day before coming to work as the cat would not let the kittens suckle. Serum from the cat had high antibody titres to phase I and phase II Coxiella burnetii antigens. The attack rate among the employees where the cat owner worked. 13 of 19 (68%), was higher than that of employees elsewhere, 3 of 13 (28%) [P <0·01]. The cat owner's wife and son also developed Q fever. None of the family members of the other employees with Q fever was so affected.

We conclude that this outbreak of Q fever probably resulted from exposure to the contaminated clothing of the cat owner.

From December 1982 to March 1986 a group of 80 children between 0 and 3 years old who lived in the peripheral area of Belém, Brazil, were followed up for episodes of diarrhoea. A total of 441 diarrhoeal episodes were recorded and 36 (8·2%) were associated with rotavirus. This agent was the only pathogen in 50% of rotavirus-related episodes of acute diarrhoea, and strains were characterized by analysis of RNA in polyacrylamide gels. Forty-one belonged to subgroup II (long pattern) and five to subgroup I. Reinfections by rotavirus were noted in 12 children involving either the same or different subgroups. Ten distinct electrophoretypes were detected in the study period and the predominant one had the ‘1N2L’ profile. The cumulative age-specific attack rate for diarrhoea reached 2–8 by the end of the first year of life; a frequency of 2–3 episodes of diarrhoea per child per year was observed throughout the complete investigation. In comparing the age-specific attack rates for diarrhoea between breast-fed and bottle-fed children, a peak at 6 months of age was noted in the former, and at 1 month in the latter. A comparison by Fischer's exact test (P = 0·21) provided no evidence for protection against clinical rotavirus disease by maternal milk. By the same test, however (P = 0·021), we found significant evidence that early rotavirus infections were more likely to be asymptomatic and that infections after 4 months were more likely to be symptomatic. The clinical picture in children with rotavirus-related diarrhoea was more severe than in those suffering from acute diarrhoea due to another agent.

A seroepidemiological study of the prevalence of mumps virus specific antibodies reveals a pattern of endemic peristence on the island of St Lucia in the West Indies. In the unvaccinated population the proportion seropositive rose rapidly in the child age classes to attain a stable plateau close to unity in value in the teenage and adult age groups. The average age at infection was estimated to be between 3 and 4 years of age and the average duration of detectable levels of maternally derived antibodies was approximately 3 months. Analyses based on mathematical models of the transmission dynamics of the virus suggest that in excess of 75% of each cohort of 1-to 2-year-old children must be effectively immunized to eliminate mumps virus transmission. A mumps radial haemolysis test, developed for quantitative measurements of antibody, is discussed.